Headlights surging/pulsing

[Wiggley]

I have a 2005 GL1800 and my headlights surge/pulse, noticed while driving to work at night. I have a new battery and the connections are tight. I have had the alternator tested and that is putting out 14+ volts as it should. Any suggestions as would could be causing this. The lights don't dim much but appear to be flickering what at idle or under load. I have also checked the connections to all the headlight bulbs and they are on tight.

[virgilmobile]

I tend to believe it's the alternator.
It may put out 14 volts but was it steady under a load test?Digital meters often won't show slight fluctuations but a analog meter will.
I just can't think of anything on the bike that can be pulsing like you describe.
A simple test...If you see it pulse at a idle..disconnect the alternator and see if it's still doing it or the alternator is causing the problem.

[Wingsconsin]

This may not be the cause -- but this is something I found on my '02 last week.
I burned out the right side headlight after only 1 year and about 13,000 miles.
When I looked at the adaptor I noticed it was melted a little bit (excess heat build up)
[attachment=2]IMG_20160630_204015006_zps78mr7zca.jpg[/attachment]

Then I looked inside and noticed the melted side was discolored as well from the heat ---
[attachment=1]IMG_20160630_204019924_zpsl2igahju.jpg[/attachment]

So I ordered new adaptors and noticed the new design is different with a plastic bar between the 2 male prongs to help keep them tight I think.
I believe they loosen up from vibration and this causes a bad connection causing poor lighting or excess heat and premature bulb burn out..

[attachment=0]IMG_20160630_203955550_zpslj6az1fb.jpg[/attachment]

[Wiggley]

I'll try that and see what it does. I have 122,000 miles on it so I figured it might be the problem. I had the dealer test it and they told me it tested fine. 14+ volts. I didn't ask if that was idle or load. I will have to check. Thanks.
I will have to look at my light sockets. I seem to burn bulbs out at least once a year I end up replacing my bulbs. Never at the same time. I just change as needed. Never thought to look at the adapters. Thanks.